JP2737021B2 - Drive wheel torque control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention (1) Field of the Invention The present invention relates to a drive wheel torque control device used for traction control for preventing excessive slip of a drive wheel.

(2) Prior Art In a so-called traction control system for preventing excessive slip of a driving wheel at the time of starting or accelerating a vehicle, feedback control of a throttle valve is performed when excessive slip of a driving wheel occurs, and output of an internal combustion engine is limited. When the excess slip becomes a large value that cannot be absorbed only by controlling the throttle valve, the output of the internal combustion engine is further limited by using fuel cut together.

(3) Problems to be Solved by the Invention However, during traction control, the initial throttle opening when returning from the fuel cut state to the feedback control of the throttle valve is determined by the drive wheels until a predetermined time elapses after the fuel cut enters. Is determined by estimating the road surface state from the torque state of the vehicle, the error may be estimated to be larger than the actually required initial opening due to an error caused by the uneven road surface state (coefficient of friction). . Further, if the friction coefficient of the road surface decreases between the time when the initial opening of the throttle valve is determined and the time when the fuel cut is returned, the initial opening when the fuel cut is returned may be excessive. If the initial opening of the throttle valve is too large for such a reason, the excessive slip of the drive wheel will be excessive when returning from fuel cut, and the vehicle will re-enter the fuel cut, causing the problem of repeated fuel cut-in and return. I do.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to avoid the inconvenience of repeated fuel cut rush in a drive wheel torque control device using both fuel cut and feedback control of a throttle valve. .

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a method for controlling an output of an internal combustion engine connected to a drive wheel when an excessive slip of the drive wheel is detected. A drive wheel torque control device that controls the excessive slip by an output reduction unit that reduces,
The output reduction means includes means for opening and closing the throttle valve to perform feedback control when excess slip exceeds the first determination value, and fuel cut when the excess slip exceeds a second determination value larger than the first determination value. Means for performing fuel cut by determining that the condition is satisfied, and means for determining that the fuel cut return condition is satisfied when the excess slip falls below a third determination value smaller than the second determination value and returning from fuel cut; Means for calculating the throttle feedback initial opening at the time of fuel cut return from the drive wheel generated torque and the excess torque consumed by excessive slip of the drive wheels, and the fuel cut condition is re-established until a predetermined time has elapsed from the time of fuel cut return. When the condition is satisfied, means for determining that the re-fuel cut condition is satisfied, and return from the re-fuel cut. The first, characterized in that the throttle feedback initial opening and means for selecting the following throttle opening at the time of the re-fuel cut rush of time.

Further, in addition to the first feature, the present invention further comprises, when the fuel cut return condition is satisfied, prohibiting the fuel cut return until the throttle valve is driven to near the fuel cut return initial opening. And

Further, according to the present invention, in addition to the first feature, the third feature is that the number of fuel cut cylinders when the fuel cut condition is satisfied is set according to the driving wheel slip state during the fuel cut.

Furthermore, in addition to the first feature, the present invention has a fourth feature that the number of fuel cut cylinders when the re-fuel cut condition is satisfied is set to be equal to or less than the number of fuel cut cylinders when the normal fuel cut condition is satisfied. And

(2) Operation According to the first feature, when the drive wheel slip exceeds the first determination value, feedback control of the throttle valve is performed to suppress excessive slip of the drive wheel, and the drive wheel slip is reduced to the first wheel slip. When the value exceeds a second determination value larger than the determination value, fuel cut is performed to further suppress excessive slip. When the drive wheel slip is reduced by the fuel cut and becomes lower than the third determination value, the control returns from the fuel cut to the feedback control of the throttle valve.
At this time, when the fuel cut is reentered within a predetermined time after the fuel cut return, the throttle opening in the feedback control at the time of the return is set to be smaller than the throttle opening at the time of the fuel cut reentry. . This prevents repeated fuel cuts.

According to the second feature of the present invention, during fuel cut, when the throttle valve is driven to open to the initial throttle opening at the time of fuel cut return, the time until the initial throttle opening is achieved is achieved. Fuel cut return is prohibited. As a result, even when the speed of the driving mechanism of the throttle valve is not sufficiently high and the fuel cut is completed in a short time, the feedback control is always started from the predetermined throttle opening at the time of the fuel cut return, and the fuel cut return is performed. Excessive driving wheel torque is prevented.

Further, according to the third feature of the present invention, the number of fuel cut cylinders is determined based on the slip state of the drive wheels, so that an optimum drive wheel torque suitable for the slip state can be obtained.

Furthermore, according to the fourth aspect of the present invention, the number of fuel cut cylinders at the time of re-fuel cut re-entry is limited, so that the drive wheel torque is prevented from being reduced more than necessary.

(3) Example Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 is a schematic configuration diagram of a vehicle equipped with the present control device. The vehicle includes a pair of drive wheels Wr and a pair of driven wheels Wf driven by an internal combustion engine E. The driven wheel Wf is provided with a drive wheel speed detector 1 and a driven wheel speed detector 2 for detecting the speeds V _W and V _V , respectively. The internal combustion engine E is provided with a rotation speed detector 3 composed of a gear and an electromagnetic pickup for detecting the rotation speed Ne of the crankshaft, and a gear position detector 5 for detecting the gear position of the transmission 4. With
An intake The passage 6 is provided a throttle valve 9 driven to open and close the connected to the intake pipe pressure detector 7 and the pulse motor 8 for detecting an intake pipe pressure P _B, fuel is further to the downstream end of the intake passage 6 Fuel injection valve 11 with cutting means 10
Is provided. In the vicinity of the internal combustion engine E, the atmospheric pressure P _A
Is provided with an atmospheric pressure detector 12 for detecting the pressure. And
The drive wheel speed detector 1, the driven wheel speed detector 2, the rotation speed detector 3, the gear position detector 5, the intake pipe internal pressure detector 7,
The pulse motor 8, the fuel cut means 10, and the atmospheric pressure detector 12 are connected to an electronic control unit U composed of a microcomputer.

FIG. 3 shows a quantum control unit U for calculating the detection signals input from the respective detectors based on a control program and driving the fuel cut means 10 and the pulse motor 8. The electronic control unit U includes a central processing unit (CPU) 13 for performing the arithmetic processing, a read-only memory (ROM) 14 storing the control program and data such as various maps, and a detection signal of each detector. A random access memory (RAM) 15 for temporarily storing the calculation results, the above-mentioned detectors, that is, a drive wheel speed detector 1, a driven wheel speed detector 2, a rotation speed detector 3, a gear position detector 5, and an intake pipe It comprises an input section 16 to which the pressure detector 7 and the atmospheric pressure detector 12 are connected, and an output section 17 to which the pulse motor 8 and the fuel cut means 10 are connected. Thus, the electronic control unit U performs arithmetic processing on the respective detection signals input from the input unit 16 and the data and the like stored in the read-only memory 14 in the central processing unit 13 based on a control program described later. The pulse motor 8 and the fuel cut means 10 are driven via the output unit 17. As a result, the output torque of the internal combustion engine E changes, and as a result, the drive wheel torque is controlled to an optimum value in order to suppress excessive slip of the drive wheel Wr of the vehicle.

Next, the details of the control of the drive wheel torque executed in the electronic control unit U will be described in detail with reference to the flowcharts of FIGS. The flowchart in FIG. 6 shows a subroutine corresponding to step S3 in FIG.
The flowchart in the figure shows a subroutine corresponding to step S53 in FIG.

4 and 5, in step S1, it is determined whether or not fuel cut is being performed based on a signal from the fuel cut means 10, and in step S2, the internal combustion engine is determined based on the detection signal of the rotational speed detector 3. E rotation speed Ne is 15
It is determined whether or not it is less than 00RPM. Then, only when fuel cut is being performed and Ne> 1500 PRM, the process proceeds to step S3; otherwise, the process proceeds to step S4.
As will be described in detail later, the fuel cut is based on the drive wheel slip V _E , that is, the driven wheel speed V _V output from the driven wheel speed detector 2 based on the drive wheel speed V _W output from the drive wheel speed detector 1.
This is performed when it is determined that the difference obtained by subtracting the reference speed _VRP as the first determination value, which is a function of, is sufficiently large and the drive wheel Wr is slipping excessively. Where V _E and V
_RP is _{V E = V W -V RP V} RP = F (V V) = K * V V where K is expressed by the constant (K> 1.0).

If the condition of Ne> 1500 PRM is not satisfied during fuel cut, a throttle feedback cycle, which is a function of the rotation speed Ne of the internal combustion engine E, is searched based on the map in step S4. In the following step S5, it is determined whether or not the cycle is a feedback cycle. If YES, the control gains K _THP ^* , K _THI ^* , and K _THP ^* , in order to perform PID feedback control of the throttle opening in step S6.
K _THD ^* is determined. In the following step S7, it is determined whether or not the previous throttle feedback has been performed, and YES
For, that is, when in throttle feedback continued, I claim in Step S8; θ _THFBI ^N is calculated based on ^{_{θ THFBI N = θ THFBI N-}} 1 -K TBI N * * V E. Incidentally, the negative sign of the second term in the above equation is for taking towards V _E is greater than zero in the positive direction. On the other hand, if NO in step S7,
If you enter new throttle feedback,
The initial throttle opening is set as follows. In step S9, it is determined whether the fuel cut has been performed last time. If YES, that is, if the fuel cut has been returned, the initial throttle opening θ _THINIT at the time of fuel cut return described later in step S10 becomes θ _THFBI. ⁰
Is replaced by When the fuel cut is not performed last time, that is, when V _E does not exceed the second determination value V _EFIH ,
In step S11, the filter value (average value) of the throttle opening up to that point Is replaced by θ _THFBI ⁰ . In the following step S12, it is determined whether or not the throttle opening θ _TO ^* that compensates for the friction of the internal combustion engine E is larger than the dashpot opening θ _{MIN.
When MIN} is larger, limit processing is performed in steps S13 and S14 so that θ _THFBI is always _equal to or more than θ _MIN . If the throttle opening θ _TO ^* that compensates for the friction of the internal combustion engine E is larger than the dashpot opening θ _MIN in step S12, limits are set in steps S15 and S16 so that θ _THFBI is always equal to or larger than θ _TO ^*. Processing is performed. When the lower limit of θ _THFBI is regulated in steps S12 to S16 as described above, in subsequent steps S17 and S18, θ _THFBI is always equal to or smaller than the throttle opening θ _WOT ^{* at} which the internal combustion engine E generates the maximum torque. Upper limit processing is performed.

Then, P term in step S19; is θ _THFBP ^N is calculated based on the ^{_{θ THFBP N = K THP * *}} V E, further D term in step S20; θ _THFBD
^N is calculated based on θ _THFBD ^N = K _THD * _E.

The following steps S21 to _S28 are performed when the ignition retard is additionally used to reduce the output of the internal combustion engine E.If the ignition retard flag F _THIGR is set in step S21, the _{process proceeds} to step S22. I term by the converted value θ _{THIGR obtained} by converting the ignition retard amount into the throttle opening; θ
_THFBI is corrected. Then, in subsequent steps S23 to S27, by the same limit processing as in the above steps S12 to S16, the corrected lower limit of θ _THFBI compensates for the friction of the internal combustion engine E, the throttle opening θ _TO ^* and the dashpot opening θ _MIN. After being limited to whichever is greater, step S28
, The ignition retard flag F _THIGR and the converted value θ _THIGR are set to 0.

Subsequently, in step S29, the feedback control amount θ _THFB
Right negative sign of the second term and the third term, positive towards the same manner as described above V _E is greater than zero in but θ _THFB = θ _THFBI -θ _THFBP -θ when calculated based on _THFBD (above formula In the following steps S30 to S36, the same limit processing as in the above steps S12 to S18 is performed, and the lower and upper limits of the feedback control amount _θTHFB are regulated.

Thus, in step S37, the feedback control amount θ _THFB is set to the target throttle opening θ _THO, and the pulse motor 8 is driven to open and close the throttle valve 9.

If the condition of Ne> 1500 RPM is satisfied during the fuel cut in steps S1 and S2, step S3, that is, the subroutine shown in the flowchart of FIG. 6 is executed by a 10 ms interrupt. First, in step S38, it is determined whether or not the previous fuel cut flag FF _{/ C} is zero. If the determination is NO, that is, if fuel cut is being performed, the throttle initialization flag _FTHINIT is also zero in step S39. It is determined whether or not the throttle initialization counter CN _THINIT is set in step S40.
Is decremented, and in the case of NO, a step S46 described later is performed.
Move to If the fuel cut flag FF _{/ C} is zero in step S38, that is, immediately after the fuel cut has been entered, the throttle initialization counter CN _THINIT is set to 100 ms in step S41 and started. Then, in a succeeding step S42, the throttle initialization flag F _THINIT is reset to zero.

By the way, in steps S43 and S44, the drive wheel slip change rate
Maximum value _EM at 100 ms for _E and total torque of drive wheels At 100 ms Is determined. That is, the driving wheel slip V _E which is calculated based on a driven wheel speed V _V output from the driving wheel speed detector 1 driving wheel speed V _W and the driven wheel speed detector 2 output from the
As a result of comparing the previous value and the current value of the drive wheel slip change rate _E , which is a derivative value of the current value, and updating the value to a larger value, the maximum value _{EM in} 100 ms is obtained. The rotation speed Ne of the internal combustion engine E output from the rotation speed detector 3 and the intake pipe internal pressure detector 7
There engine total torque TQ _OUT is calculated from the intake pipe pressure P _B to be output, this mission transfer coefficients determined in response to the output signal of the gear position detector 5 K _M and the gear ratio G /
By multiplying R, the total wheel torque is Is calculated.

Drive wheel total torque obtained in this way Result of comparing the previous value with the current value of
Maximum value at 100 ms Is required.

Next, in step S45, the effective torque TQ _INIT used for accelerating the vehicle (that is, the total torque of the driving wheels) Minus the excess torque consumed by the excess slip of the drive wheel Wr) is the maximum value _{EM of the} change rate of the drive wheel slip and the maximum value of the total torque of the drive wheel obtained in step S44 described above. Is searched from the map. Next, in step S46, it is determined whether or not the throttle initialization counter CN _THINIT is zero, that is, whether 100 ms has elapsed. If YES, the throttle initialization flag F _THINIT is set in step S47. Then, in the following step S48, the initial throttle opening θ _THINIT is calculated by the following equation.

Here dTH / DTQ is a correction coefficient for the engine torque to the throttle opening change, K _PA is atmospheric pressure correction coefficient.

When the initial throttle opening θ _THINIT is obtained in this way, in the next steps S49 to S52, the minimum value is limited to θ _T0 ^* and the maximum value is limited to θ _WOT ^* in the same manner as described above. You.

When the throttle feedback control is newly started after returning from the fuel cut in step S10 in FIG. 4 described above, the initial throttle opening θ _THINIT is used as the initial throttle opening.

Now, in step S3 of FIG. 4, the initial throttle opening θ
_{When THINIT} is determined, it is determined in step S53 whether the current fuel cut is the first fuel cut or the re-fuel cut, and if it is the first fuel cut,
In step S54, the initial throttle opening θ _THINIT obtained in step S3 is set as the target throttle opening θ _THO at the time of fuel cut return. If it is determined in step S53 that re-fuel cut is to be performed, in step S55, the target throttle opening θ _THO ^N-1 at the time of re-fuel cut entry and the initial throttle opening θ _THINIT at the time of re-fuel cut return are _determined . The smaller of the _two is selected as the initial throttle opening θ _THINIT at the time of returning from the fuel cut, and the selected initial throttle opening θ _THINIT is the target throttle daily angle θ _THO at the time of returning from the fuel cut at step S54.
Used as Therefore, the target throttle opening at the time of returning from the fuel cut is always smaller than the target throttle opening at the time of the reentry, so that the inconvenience of repeatedly performing the fuel cut is avoided.

FIG. 7 is a subroutine for determining fuel cut and determining the number of fuel cut cylinders. First, when it is determined in step S56 that fuel cut is not being performed,
Step S57 on whether the driving wheel slip V _E exceeds the second determination value V _BFIH, or even the V _E is equal to or less than V _EFIH,
In step S58, the drive wheel slip change rate _E is a reference value.
If it exceeds _BFIH , the fuel cut flag _{FF / C} is set in step S59, and fuel cut is started.
Subsequently, in step S60, it is determined whether a re-fuel cut timer described later is counting 500 ms. If YES, that is, if re-fuel cut is being performed, the number of fuel cut cylinders is determined to be three in step 61. By
Extremely reduced drive wheel torque during refuel cut entry is avoided. In addition, when the re-fuel cut timer is not counting, that is, when the fuel is cut for the first time, or for a predetermined time (500 m
s) When the time has elapsed, go to step S62. And the reference value R _{F / C} are compared, and the number of fuel cut cylinders at the time of fuel cut entry is determined according to the slip state.

On the other hand, if it is determined in step S56 that fuel cut is being performed, the following steps S64 to S71 determine whether three or six of the six cylinders of the internal combustion engine E are to be fuel cut. Control is performed. That is, if the number of fuel-cut cylinders in step 64 is three of the six cylinders, and if a predetermined time has elapsed in step 65, it is determined in step S66 whether the drive wheel slip change rate _E is positive or negative. _{If E} is positive, that is, if the drive wheel slip _VE is increasing, the number of fuel cut cylinders is increased to six in step S67 to reduce the torque of the internal combustion engine E. Further, even if the drive wheels slip change rate _E is negative, when the driving wheels slip V _E is greater than the second determination value V _EFIH in step S68, similarly the number of fuel cut cylinders 6 at step S67 To be increased. On the other hand, when the number of fuel cut cylinders is six in step S64, if it is determined in step S69 that the drive wheel slip change rate _E is smaller than the reference value _EFIL and that a predetermined time has elapsed in step S70. In step S71, the number of fuel cut cylinders is reduced from six to three. Thus, the optimum number of fuel cut cylinders is selected according to the slip state of the drive wheel Wr at that time.

Next, the driving wheel slip V _E at Step S72 the third determination V
It is determined whether it is below _EFIL, and in the case of NO, fuel cut is continued as it is. Further, when the drive wheel slip V _E is below a third alternative value V _EFIL in step S72, the step S73
Is the deviation θ between the actual throttle opening and the target throttle opening.
_It is determined whether _CMD has become smaller than the reference value θ _CMDFI ,
Fuel cut is continued until the deviation θ _CMD falls below the reference value θ _CMDFI . Thereby, the response delay of the throttle valve 9 due to the driving speed of the pulse motor 8 and the like,
Fuel cut return is performed before the throttle valve is sufficiently closed to avoid repetition of fuel cut entry and return. Then, when it is confirmed in step S73 that the throttle valve 9 has been sufficiently closed, step S7 is executed.
In 4 the fuel cut timer is set to 500 ms and started, and in step S75 fuel cut return is performed and the fuel cut flag F _{F / C} is reset to zero.

Next, the operation described above with reference to the flowchart will be further described with reference to the time chart of FIG.

When the accelerator pedal is depressed and the throttle opening θ _TH is opened to the accelerator pedal opening, the vehicle body is accelerated and the driven wheel speed V _V gradually increases. At this time, by driving wheel Wr is slipping state, the driving wheel speed V _W exceeds a first determination value V _PR exceeds the follower wheel speed V _V (A point),
The throttle feedback control is started, and the throttle opening θ _TH starts to decrease. However, when the drive wheel speed V _W further increases and exceeds the second discrimination value _VEFIH (point B), the _vehicle enters the fuel cut and the output torque of the internal combustion engine is greatly reduced, and the drive wheel speed V _W eventually decreases. Begin to. The throttle initial opening at the time of fuel cut recovery is calculated within 100 ms from the fuel cut entry, and the throttle valve is driven in advance toward the throttle initial opening. When the driving wheel speed V _W is less than the third determination value V _EFIL (C point), the throttle feedback control is started by returning from the fuel cut from the throttle initial opening. At this time, the fuel cut is not restored until the throttle valve is driven to the target opening θ _THO .

Drive wheel speed V within 500 ms after the return from fuel cut
When _W exceeds again the second determination value V _EFIH (D point), it entered the re fuel cut, the driving wheel speed V _W starts to decrease again.
When the driving wheel speed V _W is less than the third determination value V _EFIL (E point), and returning from the re-fuel cut procedure returns to the throttle feedback control. At this time, the throttle initial opening is restricted to the smaller of the throttle initial opening Q calculated during 100 ms from the re-fuel cut entry and the throttle opening P at the re-fuel cut entry ( FIG. 8 shows a case in which the initial throttle opening Q is used as it is), and repetition of fuel cut entry and return is prevented.

C. Effects of the Invention As described above, according to the first feature of the present invention, when the fuel cut is reentered within a predetermined time after the fuel cut is returned, the throttle feedback initial opening at the time of the return is reduced to the above-mentioned value. The throttle opening is set to be smaller than the throttle opening at the time of re-fuel cut entry. This suppresses an excessive increase in the initial throttle opening at the start of the feedback control, and prevents repeated occurrence of fuel cut.

Further, according to the second feature of the present invention, even if there is a delay in the speed at which the throttle valve is driven to close to the initial opening, the fuel cut return is prohibited until the initial opening is achieved. At the time of fuel cut return, feedback control is always started from a predetermined throttle initial opening. Thus, the inconvenience of returning from the fuel cut before the throttle valve is driven to close to the initial opening degree and increasing the drive wheel torque is prevented.

Further, according to the third feature of the present invention, the number of fuel cut cylinders is determined based on the slip state of the drive wheels, so that an optimum drive wheel torque suitable for the slip state can be obtained.

Furthermore, according to the fourth aspect of the present invention, the number of fuel cut cylinders at the time of re-fuel cut re-entry is limited, so that the drive wheel torque is prevented from being reduced more than necessary.

[Brief description of the drawings]

1 is a diagram corresponding to the claims of the present invention, FIG. 2 is a schematic configuration diagram of a vehicle equipped with the present control device, FIG. 3 is a block diagram showing an electronic control unit, and FIGS. 4 and 5 are throttle valves. Flowchart of feedback subroutine,
6 is a flowchart of a subroutine for obtaining an initial opening in throttle valve feedback, FIG. 7 is a flowchart of a subroutine for determining fuel cut and determining the number of fuel cut cylinders, and FIG. 8 is a time chart for explaining the operation. . 101 ... internal combustion engine output reduction means, 102 ... throttle feedback control means, 103 ... fuel cut entry / return determination means, 104 ... throttle initial opening degree calculation means, 105
...... Re-fuel cut determination means, 106 ... Throttle initial opening limit means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 43/00 301 F02D 43/00 301K

Claims (4)

(57) [Claims] When an excessive slip of a driving wheel is detected,
A drive-wheel torque control device that suppresses the excessive slip by an output-reducing means (101) that reduces the output of an internal combustion engine connected to the drive wheel, wherein the output-reducing means (101) is configured to reduce excessive slip. Means (102) for opening and closing the throttle valve to perform feedback control when the value exceeds one discrimination value;
It is determined that the fuel cut condition is satisfied when a second determination value greater than the determination value is exceeded, and fuel cut is performed. When excess slip falls below a third determination value smaller than the second determination value, it is determined that the fuel cut return condition is satisfied. Means (103) for returning from the fuel cut, and means for calculating the throttle feedback initial opening at the time of fuel cut recovery from the drive wheel generated torque and the excess torque consumed by excessive slip of the drive wheel during the fuel cut ( 104), a means (105) for determining that the fuel cut condition is satisfied again when the fuel cut condition is satisfied before a predetermined time has elapsed from the time of returning from the fuel cut, and a throttle feedback initial value when returning from the fuel cut again. Means (106) for setting the opening to be equal to or less than the throttle opening at the time of re-fuel cut re-entry. The control device for a drive wheel torque. 2. The drive wheel torque control device according to claim 1, wherein when the fuel cut return condition is satisfied, the fuel cut return is inhibited until the throttle valve is driven to near the fuel cut return initial opening. 3. The drive wheel torque control device according to claim 1, wherein the number of fuel cut cylinders when the fuel cut condition is satisfied is set according to a drive wheel slip state during fuel cut. 4. The drive wheel torque control device according to claim 1, wherein the number of fuel cut cylinders when the re-fuel cut condition is satisfied is set to be equal to or less than the number of fuel cut cylinders when the normal fuel cut condition is satisfied.